The present invention relates to a two-part piston for an internal combustion engine, comprising a piston head and a piston skirt connected with the piston head in articulated manner, by way of a piston pin. The piston head has a piston crown that is followed by a circumferential side wall having a top land and a ring belt. There is a ring-shaped circumferential cooling channel that is disposed within the piston head, the opening of which, facing the piston skirt, is closed off with a seal element.
Pistons of this type are known from WO 92/10658 A1 and from WO 92/10659 A1. A comparable piston is furthermore known from WO 90/04094 A1.
The pistons described in these references have the common feature that the piston head and the piston skirt are connected with one another only by way of a piston pin. For this purpose, both the piston head and the piston skirt have pin bosses that have pin bores that align in the assembled state, by means of which the piston pin is guided. This type of piston, in which the piston head and the piston skirt are connected with one another in articulated manner by means of the piston pin, are also called articulated pistons. They have the advantage that the piston head, which is subject to greater stress due to the temperatures and pressures that prevail in the adjacent combustion chamber, can be produced from a different material than the piston skirt, which is at a greater distance from the combustion chamber and subject to less stress. The piston head can be produced from steel, for example, and the piston skirt from an aluminum material. This is supposed to counteract damage, for example cracks and fractures at the piston head. With these articulated pistons, the piston head has to be effectively cooled because of its great thermal stress. For this purpose, there is a circumferential cooling channel for a coolant within the piston head, approximately at the height of the top land and the ring belt.
The problem with articulated pistons is that this cooling channel is not tightly sealed, since the piston head and the piston skirt are connected only by way of the piston pin. The pistons of the stated type, known from WO 92/10658 A1 and from WO 10659 A1, solve the problem by means of a seal ring made of sheet metal, but this significantly reduces the volume of the cooling channel, so that the cooling effect is reduced. The piston known from WO 90/04094 A1 is provided with catch basins for the coolant, something that is complicated in design and does not improve the cooling effect.
The present invention is therefore based on the task of making available a piston that demonstrates an improved cooling effect while being simple to produce.